The Highland Valley Trail in San Dieguito River Park follows Highland Valley Road.

Geocaching on Highland Valley Trail

Trail head: The Highland Valley Trail is a lovely trail even if you don’t search for the geocaches. It runs along Highland Valley Road in Rancho Bernardo through an agricultural area, a pastoral scene filled with oak trees that miraculously survived the Witch Creek fire. Find the trail head at Highland Valley and Pomerado roads; Pomerado Road is an exit off Interstate 15.

Length: Two miles one way; allow at least two hours.

Difficulty: Easy.

Before you go: Check geocaching.com to locate hidden geocaches wherever you want to search. San Dieguito River Park’s “The Mystery Witch Hunt” geocache GPS coordinates should be posted on its Web site, sdrp.org , as well as geocaching.com.

Enjoying nature is often reward enough from hiking. But the global game called geocaching adds a little high-tech treasure hunting to the activity.

A few of us joined park rangers Ken Colburn and Jacob Gibbs of San Dieguito River Park last month for a geocache hunt on the Highland Valley Trail and discovered an amazingly fun pastime.

Geocaching is a global phenomenon that began May 2, 2000. That’s when “the great blue switch” that controlled selective availability was flipped by the government, essentially upgrading 24 satellites around the globe so that the accuracy of Global Positioning Satellite technology improved exponentially, according to the book “The Complete Idiot’s Guide to Geocaching.”

A day later, Dave Ulmer, a computer consultant, wanted to test the new accuracy, so he hid a container in the woods near Beaver Creek, Ore., and posted its GPS coordinates on an Internet GPS users group page. Inside his container he placed a logbook, pencil and some prizes, including videos, books and a slingshot.

Within three days, two readers used their GPS devices to find the container and shared their experiences online. Mike Teague, the first person to find Ulmer’s stash, began gathering online posts of coordinates around the world, documenting them on his personal home page. The original “GPS Stash Hunt” soon became “geocaching,” and a new game began.

Today, players around the world register their geocache coordinates on geocaching.com . There are more than 955,000 documented geocaches around the globe, and the number rises daily.

There are several rules of etiquette involved in geocaching. View videos of the game and its rules at geocaching.com or rei.com , an outdoor equipment store that sells geocaching materials. The most important rules are:

• Leave the geocache better than you found it; if you take something from the geocache, put something of equal or greater value back in it.

• Be mindful of nature when placing and retrieving so as not to disturb the environment.

• Sign your name on the log at each geocache.

• Put the geocache back exactly where you found it.

Additionally, there are “travel bugs,” which are essentially numbered dog tags made for the sport. They are meant to be taken and moved to another cache. The person who finds a travel bug logs its number on the Web site and agrees to move it to another cache, so the original owner can trace its movement sometimes thousands of miles around the world.